Adriamycin Cardiotoxicity: (Myers, Eliot, Brooks, Locker, Doroshow, McGuire). This laboratory has recently proposed that adriamycin cardiotoxicity results from free radical generation during drug metabolism. The basic observations supporting this contention have been published in Science 197: 165 (1977). We are currently examining the endogenous defenses of cardiac tissue against free radical damage to see what role they might play in the clinical pattern of cytotoxicity. Finally, we are actively engaged in the design of a clinical trial testing the ability of various free radical scavengers such as Vitamin E to ablate adriamycin cardiac toxicity.